The problem at the very start (as always) is definitions.
You're right that ID isn't a "scientific theory." Neither is the idea that from inorganic materials, life developed and evolved, baby-step-by-baby-step to we'uns.
Evolution is a theory about "natural history," not science. ID is a theory about "design," not science. The problem with origins is that you have so many different disciplines that have a bearing on the questions(s) that everybody wants to make it "their own." People want to call it "science" because in the popular mindset that makes it authoritative, and above questioning. (Like "religion" might have been 600 years ago).
But science is what you do by experimentation and observation. History (and natural history) is what you surmise from the relevant artifacts and data accumulations. And, due to the nature of evolutionary theory (vast change over great amounts of time) we'll have to wait a long long time for the first "scientific" evolutionary experiment. ID has its own set of problems, but the point is....so does everyone else.
There's nothing wrong with saying: "There's so much that we're just clueless about.". If the biology texts and teachers started from that, it would be cool. My high school biology indoctrinator started with the attitude that "this is a slam-dunk, and God is an A-hole." He was highly regarded by his fellows.
This is not true. It is a claim in the ToE that people, gorillas, and chimps share a common ancestor that is not also an ancestor of monkeys. Monkeys make vitamin C, but people and apes cannot. Assuming that ToE is true, one *deduces* that the *same mutation* is responsible for the fact that we and the (other) apes can't make ascorbic acid.
In fact, when the relevant parts of human, chimp, and gorilla DNA were analyzed, the prediction made by ToE, as always, proved to be correct.
In other words, the facts had a chance to falsify ToE. Instead, they confirmed it.
This same sort of thing keeps happening, over and over. There have been thousands of observations, of fossil digs and genomes, and never once has one of them shown ToE to be false.
Unfortunately for the ID-ists, ID cannot in principle be falsified:
Wow, chimps and people share a mutation that blocks vitamin C formation. What a subtle creator!
Wow, chimps and people have different mutations that blocks vitamin C formation. What a subtle creator!
Therefore, ID isn't even a theory - it's an untestable hypothesis, mere armchair speculation.
ID has its own set of problems, but the point is....so does everyone else.
It's main problem is that it's content-free; there is no possible observation, in a fossil dig or a lab, that could, if it went against prediction, show ID to be false. Until there are, it has no place in the classsroom, outside of rhetoric class.